Tank for cracking mineral oil



Feb. 24, 1931. A. E. PEW. JR.. ET AL 1,794,200

TANK FOR CRACKING MINERAL OIL Filed June 26, 1929 Patented Feb. 24, 1931 UNITED STATES PATENT 7 OFFICE ARTHUR IEW, JR., OF BRYN MAWR, AND HENRY THOMAS, OF RIDLEY PARK,

PENNSYLVANIA, ASSIGNORS 'IO SUN OIL COMPANY, OF PHILADELPHIA, PENN ST- VANIA, A CORPORATION OF NEW JERSEY TANK non cnacxme MINERAL on.

' Application filed. June 26,

In an application filed August 18, 1928, Serial No. 300,441, we describe a process and apparatus for cracking mineral oil. The apparatus comprises a boiler, adapted to generate mercury vapor, connected, by outflowing vapor lines and by back-flowing condensate lines, with a plurality of tanks, each of which contains a coil through which flows the oil that is to be heated and cracked. The coils of the several heating units are arranged in series. In each heating unit, heat exchange with the oil effects condensation of the mercury vapor, the condensate returning to the boiler through the back-flow connection. The oil in the coil is under a high superatmospheric pressure, say 1200 pounds to the square inch, while the tank space is under a relatively low pressure, say eighty pounds to the square inch.

The heating unit disclosed in said application comprises features of independent novelty and utility, and forms part of the,

subject matter of this application.

The drawing shows a preferred embodiment of the invention in side elevation, partly broken away.

The heating unit comprises a tank shell a and a coil (2. The coil 11, or all except the end return bends or headers thereof, is contained within the tank and comprises, preferably, a single length of pipe, which may be, say, over seven-tenths of a mile in length. It is impracticable to fixedly secure straight pipe sections to the opposite end heads of the tank, since provision must be made for the unequal expansion of the tube sections and the tank.

The shell a comprises a cylindrical body and circular dished end heads 6 and c, and has openings at the top communicating with the mercury vapor inflow pipes 10, and a connection at the top with a pipe 11 on which is a relief valve 12 to relieve internal pressures. The pipe sections d forming a coil are, at one end, welded to head I) from either the outside or inside and are connected one to another by headers'or return bends e, which are removable for cleaning purposes. Inside the steel 9, which has been machined. A cirthe steel ring. The other ends of the pipe sections are welded to the inside head of a box it, and headers or return bends 7 connect adjacent pipe sections and, like headers c, are removable. Welded to the other head of box his a pipe or neck 2', which extends out through head 0 and is welded thereto. At the outer end of neckz' is a cover plate 3' bolted to a flange on the neck to make a tight. connection. Installed in neck 2' is an expansion joint k-of the well known accordian type.

Mercury vapor fills the s ace around the tubes composing the coil d ut cannot penetrate the box '71,. It is thus possible, without hazard, for a man to enter box h through neck 21 and remove the return bends 7 when the tank is not in operation. Mercury vapor, however, will penetrate, through the sliding fit between box it and ring 9, into the space between box it and end head 0. Such vapors condense and are withdrawn through pipe 14. The main condensate flows out through line 13.

The heating unit, as far as above described, is fully disclosed in our said application, Serial No. 300,441.

From the neck i of box h extends a pipe 14' leading, through a valve 15, to any source of compressed air, which is admitted to the neck 2' until the pressure therein and in box it equals the mercury vapor pressure within the tank. The flat head of the box h is therefore subjected on opposite sides to balanced pressures, thereby relieving it of undue stresses. A pressure-regulatin relief valve 16 prevents the pressure within the box it from increasing due to increase of temperature.

It is obvious that the heating unit is capable of use not only in series with other similar units, but it may be used alone, or it may be one of a plurality of tanks arranged in multiple.

It is possible to slightly bend or bow the tubes 0?, to have the box it in fixed relation to the tank, and to make the end head 6 of the tank and the head of box It strong enough, by the use, for example, of staybolts, to force the tube to bend and thus take up the expan box in the tank between said end heads, each coil comprising pipe sections connected at r the ends by return bends, the pipe sections being welded at one end of the coil to the wall of the box, the return bends at such end of the coil being contained within the box, the box comprising an extension projecting through an end head of the tank and through which access may be had to the interior of the box to enable the return bends to the applied and removed and a removable cover on the outer end of the box extension.

2. An oil heating unit comprising a coil of pipe and a tank having end heads and enclosin the major part of the coil, and a box slidab e in the tank between said end heads,-

each coil comprising pipe sections connected at the ends b return bends, the pipe sections being welde at one end of the coil to the wall of the box, the return bends at such end of the coil being contained within the box, the box comprising an extension projecting through an end head of the tank and throu h which access may be had to the'interior of t e box to enable the return bends to be applied and removed and a removable cover on the outer end of the box extension.

3. An oil heating unit comprising a pipe coil and a tank enclosing the major part of' the coil and rovided with end heads, and a box body in t 1e tank between said end heads, each coil comprising pipe sections connected at the ends by return bends, the pipe sections being welded at one end to one end head and at the other end to a wall of the box body, the return bends at one end being positioned outside said end head and at the other end being contained within the box body, and an extension from the box body pro ecting through and secured to the other end head and having an opening through which access may be had to the interior of the box and a removable cover on the outer end of the box extension.

4. An oil heating unit comprising a pipe coil and a tank enclosing the major part of the coil and provided with end heads, and a box body slidable in the tank between said end heads, each coil comprising pipe sections connected at the ends by return bends, the pipe sections being welded at one end to one end head and at the. other end to a wall of the box body, the return bends at one end being positioned outside said end head and at the other end being contained within the box body, and an extension from the, box body projecting through and secured to the other end head and havin an opening through which access may befiiad to the interior of the box, said extension comprising an expansion joint which permits the box body to slide as specified and a removable cover on the outer end of the box extension.

5. An oil heating unit comprising a tank, a box therein, and a coil of pipe secured at one end to an end head of the tank and at the other end to the box, said tank having an' said end head and box and a valve-controlled.

pipe communicating with the interior of the box and through which pressure fluid may be admitted to balance the fluid pressures on opposite sides of the box head.

7. An oil heating unit comprising a ank, a box therein, a coil of pipe secured at one end to an end head of the tank and at the other end to the box, said tank having an inlet for a condensible heating-vapor and an outlet for condensate both located between said end head and box, a valve-controlled pipe crmnnunicatiug with the interior of the box and through which pressure fluid may be admitted to balance the fluid pressures on opposite sides of the box head, and a pressureregulating valve adapted to prevent increase of fluid pressure within the box due to rise in temperature.

8. An oil heating unit comprising a coil of pipe and a tank enclosing the major part of th coil, and a box slidable in the tank and to which one end of the coil is secured, said box having an opening throu h which access may be had to the interior 0% the box frpm outside the tank, the coil-containing part of the tank having an inlet for a condensible heating medium and an outlet for condensate, said box being slidable in the tank and forming with the tank a space separate from the coil-containing chamber having the inlet for a condensible heating medium, said space having an outlet for condensate.

9. An 'oil heating unit comprising a tank having end heads, a box slidable in the tank between said end heads, and a pipe coil extending within the tank between one and head and the box; the coil and the interior of the tank being in heat exchange relation and the slidable box being closed from communication with both the pipe coil and the interior of the tank.

10. An oil heating unit comprising a tank ening through which access may be had to the interior of the box from outside the tank.

11. An oil heating unit comprising a tank having end heads, a box slidable in the tank between said end heads, and a pipe coil extending within the tank between one end head and the box; the coil and the interior of the tank being in heat exchange relation and the slidable box being closed from communication with both the pipe coil and the interior of the tank, said box comprising an extension therefrom rojecting through one and head of the tank said extension being provided with a closure which is removable to allow access to the interior of the box.

12. An oil heating unit comprising a tank having end heads, a box slidable in the tank between said end heads, and a pipe coil extending within the tank between one end head and the box; the coil and the interior of the tank being in heat exchange relation and the slidable box being closed from communication with both the pipe coil and the interior of the tank, said box comprising an extension projecting through and secured to one end head of the tank, said extension comprising an expansion joint permitting the box to slide as specified.

In testimony of which invention, we have hereunto set our hands, at Philadelphia, Pennsylvania, on this 22nd day of June, 1929.

ARTHUR E. PEW, JR. HENRY THOMAS. 

